High energy density energy storage and discharge device

ABSTRACT

An electrically transductive device, including a substrate having an electrically conducting surface portion, a first film of semiconducting nanoparticles positioned on the electrically conducting portion and further including a first plurality of close packed first generally spherical particles defining a first plurality of interstices and a second plurality of second, smaller generally spherical particles substantially filling the plurality of interstices, and a first coating of electrically conductive metal deposited over the first film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. provisional patentapplication Ser. No. 61,550,893, filed on Oct. 24, 2011; copending U.S.provisional patent application Ser. No. 61/495,626, filed on Jun. 10,2011; and to copending U.S. provisional patent application Ser. No.61/418,232, filed on Nov. 30, 2010.

BACKGROUND

Electrophoretic deposition is a process by which particles desired to beplated or deposited onto a substrate are first colloidally suspended andthen urged out of suspension and onto a substrate by means of an appliedelectric field. The desired coating material is provided as an amount ofcolloidal particles suspended in a liquid (typically aqueous) medium.The particles are imparted a surface charge, and thus migrate under theinfluence of an applied electric field to be deposited onto a chargedsubstrate, which acts as an electrode. The colloidal particles can bepolymeric, metallic or ceramic, so long as they can hold a surfacecharge.

Electrophoretic deposition may be used for applying charged colloidalmaterials to any substrate that is, or that can be made, electricallyconductive. Aqueous colloidal suspensions are typical of electrophoreticdeposition. Non-aqueous electrophoretic deposition applications arebeing explored, but are still in their infancy and are primarilyattractive for applications requiring voltages high enough toelectrolyze water, which may result in the evolution of undesiredamounts of oxygen.

Electrophoretic deposition is typically used to apply coatings tometallic items, such as machine parts, metallic structural members,containers, and the like. Current manufacturing methods for depositionof thin films onto substrates, such as silicon films for photovoltaicapplications, typically utilize a vacuum environment in order to lowerthe crystallization temperatures of the amorphous silicon material usedas a silicon source and deposited onto the substrate for subsequentheating and recrystallization. However, the electrophoretic depositionprocess is more difficult to control as the size of the suspendedparticles decreases. As coatings made up of smaller, nanoscale particleshaving interesting and useful properties are desired, there thus arisesa need to an improved electrophoretic deposition process for providingsuch coatings. The present novel technology addresses this need.

SUMMARY

The novel technology relates to an amplified piezoelectric effectresulting from quantum confined silicon and germanium nanocrystalssynthesized in a predetermined state of stress. The nanoscalepiezoelectric effect may be amplified by nanoparticles having acrystalline core surrounded by an amorphous shell and/or a crystallinecore coated by a chemically different material, crystalline oramorphous. The increase to the nanoscale piezoelectric effect arisesfrom higher relative strain induced at the interface of the core-shellnanoparticles from the difference in coefficient of thermal expansionbetween the amorphous shell and the crystal core and/or from themismatch of interatomic spacing between the vitreous shell and crystalcore. Typically, the shell compresses the core, but may alternatelycontribute tensile stresses. Particles are deposited onto a conductivesubstrate by electrophoretic deposition and self-align according totheir respective dipole moments to form a unified Weiss domainthroughout the film. Internal stress in the particles making up the filmcan be increased by intercalation of smaller atoms, such as lithium.Lithium intercalation into the nanocrystals results in a furtherincrease in internal stress and a subsequent increase in the energydensity achievable within the film. Typically, a metal film is depositedto protect the nanoparticle film. The metal contact also serves as aconduit for transferring energy stored in the film to an externaldevice.

One object of the present novel technology is to provide an improvedhigh energy density power storage and discharge device. Related objectsand advantages of the present novel technology will be apparent from thefollowing description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded view of a semiconducting nanocrystalline filmdeposited on a conductive substrate according to a first embodiment ofthe present novel technology.

FIG. 1B is an exploded view of a plurality semiconductingnanocrystalline films separated by electrically conducting layers asdeposited on a conductive substrate according to a second embodiment ofthe present novel technology.

FIG. 2 is a perspective view of an assembly for depositing the film ofFIG. 1 onto a substrate.

FIG. 3 is a process chart illustrating the fabrication of one or moredevices according to the embodiment of FIG. 1.

FIG. 4 is a TEM photomicrograph perspective view of a strained siliconnanocrystal having an amorphous silicon shell encapsulating a purifiedcrystalline silicon core.

FIG. 5 is an enlarged TEM photomicrograph view of a portion of thecrystal of FIG. 4.

FIG. 6 graphically illustrates an EDX plot for the crystal of FIG. 4.

FIG. 7A graphically illustrates an XRD plot comparing the strainedsilicon 111 crystal plane of the crystal of FIG. 4 to a standardunstrained silicon 111 plane.

FIG. 7B graphically illustrates an XRD plot comparing the strainedsilicon 111 crystal plane of the crystal of FIG. 4 to a standardunstrained silicon 111 plane, corrected for contributions from an ITOconductive layer and the amorphous glass halo and/or shell surroundingthe silicon crystal.

FIG. 8 graphically illustrated the crystal structure of strainedsilicon.

FIG. 9 is a TEM photomicrograph of a strained silicon nanocrystal havingobservable lattice planes.

FIG. 10 is a TEM photomicrograph of a plurality of strained siliconnanocrystals, each having observable lattice planes.

FIG. 11 graphically illustrates an EDX analysis of the nanocrystals ofFIG. 10. FIG. 12 graphically illustrates an XRD plot for the crystals ofFIG. 10 showing the shift of the 111 plane due to induced strain.

FIG. 13 is an SEM image of a layer of smaller (9 nm) siliconnanocrystals deposited over a layer of larger (25 nm) siliconnanocrystals.

FIG. 14 is an exploded view of a internally strained semiconductingnanocrystalline film deposited on a conductive substrate according anddefining a voltage source a third embodiment of the present noveltechnology.

FIG. 15 is an exploded view of a internally strained semiconductingnanocrystalline film deposited on a conductive substrate according andin an electrolyte medium and defining a voltage source a thirdembodiment of the present novel technology.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of thenovel technology, reference will now be made to the embodimentsillustrated in the drawings and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the novel technology is thereby intended, suchalterations and further modifications in the illustrated device, andsuch further applications of the principles of the novel technology asillustrated therein being contemplated as would normally occur to oneskilled in the art to which the novel technology relates.

Piezoelectric Effect

Piezoelectricity is the special circumstance of electrical chargebuild-up that arises in certain solid material structures due tomechanical stress. Generally, the piezoelectric effect has beenexperimentally determined to be a linear electromechanical interactionbetween the mechanical and the electrical state in crystalline materialswith no inversion symmetry. The piezoelectric effect is a reversibleprocess such that the internal generation of electrical charge resultingfrom an applied mechanical force can be reversed with the internalgeneration of a mechanical strain resulting from an applied electricalfield.

Piezoelectric Effect in Semiconductors

In semiconductors, changes in inter-atomic spacing resulting from strainaffects the semiconductors intrinsic band gap making it easier (orharder depending on the material and strain) for electrons to be raisedinto the conduction band. The piezoelectric effect of semiconductormaterials can be several orders of magnitudes larger than the analogousgeometrical effect in metals and is present in materials like germanium,polycrystalline silicon, amorphous silicon, silicon carbide, and singlecrystal silicon.

The piezo effects of semiconductors have been used for sensor deviceswith a variety of semiconductor materials such as germanium,polycrystalline silicon, amorphous silicon, and single crystal silicon.Since silicon is currently the material of choice for nearly allintegrated circuits, the use of piezoelectric silicon devices has beenan intense area of research interest.

Piezoresistive Effect in Single Crystal Silicon and Germanium

The resistance of silicon and germanium can change due to astress-induced change of geometry, but also due to the stress dependentresistivity of the material. The resistance of n-type silicon(predominant charge carriers responsible for electrical conduction areelectrons) mainly changes due to a shift of the three differentconducting vertices of the crystal. The shifting causes a redistributionof the carriers between vertices with different mobilities. This resultsin varying mobilities dependent on the direction of current flow. Aminor effect is due to the effective mass change related to shapedistortion due to change in the inter-atomic spacing of valley verticesin single crystal silicon. In p-type silicon (predominant chargecarriers responsible for electrical conduction are holes) the phenomenacurrently being researched are more complex and also demonstrate changesin mass and hole transfer.

Detailed Description of Piezoelectric Mechanism

The nature of the piezoelectric effect is rooted in the occurrence ofelectric dipole moments in solids. An electric dipole moment is a vectorquantity equal to the product of the magnitude of charge and thedistance of separation between the charges. Electric dipole moments insolids may either be induced for ions on crystal lattice sites as in anasymmetric charge environment such as in lithium tantalate and leadzirconate-titanate or may be directly carried by molecular groups suchas in organic sugar molecules. The dipole density causing polarizationis the sum of the dipole moments per unit volume of a crystal unit cell.Since electric dipoles are vector quantities (geometric objects ofspecific magnitude and direction), the dipole density P is also a vectorquantity. Dipoles near each other tend to be aligned in regions calledWeiss domains. In these aligned regions occurring between individualparticles, the particles act as a whole thus the potential and polarityof voltage and magnitude and direction of the current is equal to thesum of all individual particles making up the entire solid.

To reiterate, typically the piezoelectric effect typically occurs withan applied mechanical stress but can also be manifested by manufacturinginternal stress into certain solids. Piezoelectricity arises in avariation of the polarization strength, its direction or both. Themagnitude and direction of the charge depends on the interrelationshipsbetween the orientation of P within individual particles, particlesymmetry, and the applied mechanical stress or induced internal stress.Although the change in an individual crystal's dipole density appearsquantitatively as a variation of surface charge density upon theindividual crystal faces, the overall useful energy arising from thepiezoelectfic phenomenon is caused by superposition of the dipoledensities of the crystals that make up the entire piece of material,i.e., as a sum of the individual crystallographic unit cells that makeup a whole crystal. For example, a 1 cm³ cube of quartz with 500 lb ofmechanically applied force at the right point can produce a voltage of12500 V because the resultant force is the sum of all the individualcrystallographic unit cells that make up the whole crystal.

Power Generation in Polar Crystal Structures Synthesized in a State ofStress

There are 32 crystal classes that represent 32 possible combinations ofsymmetry operations in crystalline materials. Each crystal classincludes crystal faces that uniquely define the symmetry of the class.Of the thirty-two crystal classes, twenty-one are non-centrosymmetric(not having a centre of symmetry), and of these, twenty exhibit directpiezoelectricity. Ten of these include the polar crystal classes, whichshow a spontaneous polarization without an applied mechanical stress dueto a non-vanishing electric dipole moment associated with asymmetryinherent in their crystal structure. For polar crystals, for which thesummation of the dipole density P≠0 holds without applying a mechanicalload, the piezoelectric effect manifests itself by changing themagnitude or the direction of P or both. Stated another way, polarcrystals that can be manufactured to have internal stress willdemonstrate a piezoelectric effect without an applied mechanical load.

Restated another way, for non-polar piezoelectric crystals, an appliedmechanical load transforms the material from a non-polar crystal class(P=0) to a polar one, having P≠0 and hence gives rise to a voltagepotential and useful energy capable of powering an external device.However, crystals predisposed to an internal state of stress have aninherent polar structure for which P≠0 and hence energy can bedischarged from the structure without an applied mechanical load. Duringdischarge of electrical energy, the crystal relaxes back into itspreferred state of interatomic spacing.

Quantum Confinement in Nanoparticles

Quantum confinement in nanocrystals is an important concept to grasp.Quantum confinement in nanocrystals occurs when the physical size of theparticle is less than its characteristic exciton Bohr radius. Theexciton Bohr radius is the physical distance separating a negativelycharged electron from its positively charged hole left behind duringexcitation. When the physical size of the particle is less than thedistance the electron must travel during excitation, the material isconsidered to be quantum confined. For example, the exciton Bohr radiusfor germanium is 24.3 nm; however, it is possible to synthesizegermanium nanocrystals to be 1 nanometer in diameter. By creatingnanoparticles smaller than this characteristic distance, the electronicproperties of the nanoparticles can be tuned to discreet energy levelsby adjusting particle size. Thus, an aggregate made of particles smallerthan the Bohr radius will enjoy a greatly increased energy density. Ifthe particles are about the same size as the Bohr exciton radius, oreven a little larger, an aggregate of the particles will still enjoyincreased energy density, if not to the same degree as if all of theparticles were smaller than the exciton Bohr radius.

Another important concept to understand is that of potential wells andhow they arise in nanoparticles. Potential wells are a direct result ofsynthesizing physical particle dimensions to be smaller than theirrespective exciton Bohr radius. A potential well is the regionsurrounding a local minimum of potential energy in nanomaterials. Energycaptured in a potential well is unable to convert to another type ofenergy because it is captured in the local minimum of the potentialwell. Therefore, a body may not proceed to the global minimum ofpotential energy, as it naturally would according to the universalnature of entropy.

Energy may be released from a potential well if sufficient energy isadded to the system such that the local minimum energy for excitation issufficiently overcome. However, in quantum physics potential energy mayescape a potential well without added energy due to the probabilisticcharacteristics of quantum particles. In these cases, a particle may beimagined to tunnel through the walls of a potential well without energyadded to the system.

As illustrated in FIGS. 1A-3, the present novel technology relates to amethod of producing a coating or film 10 on a substrate 15 underconditions of ambient atmospheric composition and pressure, and ambientor slightly elevated temperature, by electrophoretically extracting 20nanoscale particles or nanocrystals 25 from a nonaqueous colloidalsuspension 30 and substantially uniformly depositing 35 thenanoparticles 25 onto the substrate 15. Typically, the coating or film10 is less than 1000 nanometers in thickness, but may be thicker. Asubstrate 15 desired to be coated is typically prepared by firstcleaning 40 the substrate 15, and then, if the substrate 15 is notsufficiently electrically conductive, coating 43 the substrate 15 with alayer of conductive material 45, such as silver or indium tin oxide(typically used to prepare optical elements, since thin layers of indiumtin oxide are substantially optically transparent).

A nonaqueous suspension 30 of nanoparticles 25 is then prepared. Theliquid suspension medium 50 is typically a polar solvent, such as2-butanol, 1,2-dichlorobenezene and/or acetone, or the like. Typically,the solvent 50 composition is selected taking into account suchproperties as its inherent dielectric constant, its Hamaker constant,its miscibility, its viscosity, and the like. More typically, a blend ofaprotic polar nonaqueous solvents 55 and protic polar nonaqueoussolvents 60 is selected to define the liquid suspension medium 50.

More typically, small amounts of an ionic liquid 65, such as 1-butyl-1methylpyrrolinium dis(perifluoromethylsulfonyl)imide, are added to thenonaqueous solvent blend 50 to facilitate deposition of nanoparticlefilms 10. A predetermined and measured amount of nanoparticles 25 isthen dispersed in the solvent blend 50. The solvent blend 50 istypically agitated until the nanoparticles 25 are generally evenly andhomogeneously dispersed to define a colloidal suspension 30. A buffersolution may be added to the colloidal suspension 30 to manage thesurface charge on the nanoparticles 25. For example, silicon particlesare negatively charged in the pH range between about 6 and about 9 whilegermanium particles are negatively charged in the pH range from about 3to about 5.

The substrate 15 is then connected to a DC power source 70 to serve as afirst electrode 75 while the DC source 70 is connected to the solventbath 30 through a second electrode or electrode array 80 immersedtherein (such as a carbon electrode) to complete an electric circuit andestablish an electric field, with the substrate 15 having an oppositecharge to that imparted to the suspended particles 25. The substrate 15is typically the cathode 75 and the carbon electrode is typically theanode 80. The electrodes/electrode arrays 75, 80 are typicallymaintained at a distance of between about 0.5 and about 4.0 centimetersapart, depending upon such variables as the desired deposition pattern,the shape of the electrodes 75, 80, the shape of the substrate 15, andthe like; however, under certain circumstances the electrode separationdistance may fall outside of the 0.5 to 4.0 centimeter range. Theapplied voltage is typically between about 3 and about 12 volts,depending on the nanocrystal particle size (typically between about 1and 1000 nanometers in dimension, more typically between about 2 andabout 50 nanometers in diameter). The particles 25 in the suspension 30will electrophoretically migrate to the substrate 15, forming asubstantially even coating 10 thereupon.

The nanoparticles 25 may be of any convenient shape and geometry, andare generally regularly shaped and are typically blocky, and, moretypically, generally spherical. Typically, the nanoparticles 25 will betightly sized, having a relatively narrow particle size distribution(PSD), to yield a coating or film 10 of nanoparticles 25 having a narrowparticle size distribution, such as, for example, wherein most of theparticles 25 fall in the 3-10 nanometer range. Alternately, the appliedvoltage, current and/or the pH of the colloidal solution 30 may bevaried to yield similar control over the size of the deposited particles25 when the colloidal solution 30 includes a substantial amount ofparticles 25 falling outside the target size range. Further, by varyingthe applied voltage and/or the pH of the medium 30, multiple layers 90of nanocrystals may be applied to a substrate 15 in a predetermined,size-specific of graduated order. The deposition process 35 is continueduntil the desired film thickness is achieved, typically for about 30seconds to about 5 minutes to yield a deposited layer 90 typically froma few hundred to a few thousand nanometers thick. Typically, thedeposition process 35 is conducted under ambient atmosphere; no vacuumis required.

Typically, the nanocrystals 25 are of very high purity, typically atleast about 99.999 percent pure, more typically at least about 99.9999percent pure, and still more typically at least about 99.999999 percentpure. The nanocrystals 25 may be monodisperse within +/−10% of thedesired diameter and may be single crystal/single grain boundarymaterials, but are not limited to these types and size dispersions. Asillustrated in FIGS. 4-8, it is also possible to deposit nanoparticles25 that have a multilayered or core/shell structure, such as acrystalline core 130 within an amorphous shell 140, wherein the shell140 compresses the core 130 to generate stress and maintain straintherein. This effective surface area of the film 10 is a function of thenanocrystalline particle size and shape and is governed by the desiredend use and does not change the method of deposition. Likewise, there isno requirement that the electrode or electrode array 80 be of equal orlarger size than the conductive substrate 75 that the nanoparticles willbe deposited upon.

EXAMPLE 1

Eighty milligrams of 9-nanometer silicon particles are suspended in 10milliliters of 2-butanol to yield a colloidal suspension with aconcentration of about 8 milligrams silicon nanoparticles/1 milliliter2-butanol. 10 milliliters of reagent grade acetone is added to thecolloidal suspension. 300 microliters of 1-butyl-1methylpyrroliniumdis(perifluoromethylsulfonyl)imide is added to the colloidal suspension.The colloidal suspension is heated to a temperature of about 40 degreesCelsius. A 1 cm×2 cm glass substrate coated with indium tin oxide andhaving a resistance of about 8 ohms/sq cm is connected to the cathode ofa DC power supply and immersed 1 cm into the colloidal suspension. Acarbon electrode is connected to the anode of the DC power supply andspaced 1 centimeter from the glass substrate in the suspension. Avoltage potential of 4 volts is applied across the electrodes andallowed to remain for 180 seconds while a silicon film having athickness of between about 500 and about 800 nanometers is deposited onthe glass substrate area that was submersed in the colloid solution.

EXAMPLE 2

Eighty milligrams of highly pure germanium nanocrystal particles wereobtained from the Universal Nanotech Corporation. The germaniumparticles were characterized by an average particle diameter of about 10nanometers were suspended in a polar protic solvent, such as MeOH, toyield a colloidal suspension. Oleyalamine is added to the colloidalsuspension to assist in maintaining the germanium nanoparticles insuspension. The colloidal suspension is typically maintained at atemperature of between about 25 and about 40 degrees Celsius A 1 cm×2 cmglass substrate coated with indium tin oxide and having a resistance ofabout 8 ohms/sq cm is connected to the cathode of a DC power supply andimmersed 1 cm into the colloidal suspension. A carbon electrode isconnected to the anode of the DC power supply and spaced 1 centimeterfrom the glass substrate in the suspension. A voltage potential ofbetween about 1.5 and about 7 volts is applied across the electrodes andallowed to remain for from about 180 seconds to about 5 minutes while agermanium film is deposited on the glass substrate area that wassubmersed in the colloid solution.

Devices made from Group IV nanoparticles 25 benefit from the unique andsize-driven physical characteristics of these nanoparticles 25,sometimes referred to as “quantum dots”. Semiconductors are materialsthat conduct electricity, but only very poorly. Unlike metals, whichhave an abundance of free electrons capable of supporting electricalconduction, the electrons in semiconductors are mostly bound. However,some are so loosely bound that they may be excited free of atomicbinding by the absorption of energy, such as from an incident photon.Such an event produces an exciton, which is essentially an electron-holepair, the hole being the net-positively charged lattice site left behindby the freed electron. In most crystals, sufficient excitons may becreated such that the freed electrons may be thought of as leaving thevalence band and entering the conduction band. The natural physicalseparation between the electron and its respective hole varies fromsubstance to substance and is called the exciton Bohr radius. Inrelatively large semiconductor crystals, the exciton Bohr radius issmall compared to the dimensions of the crystal and the concept of theconduction band is valid. However, in nanoscale semiconductor crystalsor quantum dots, the exciton Bohr radius is on the order of the physicaldimension of the crystal or smaller, and the exciton is thus confined.This quantum confinement results in the creation of discrete energylevels and not a continuous band.

Exploitation of this phenomenon, such as by coatings of nanoscalesemiconductor crystals 25, can yield such devices as photovoltaic cells‘tuned’ to specific wavelengths of photons to optimize energytransduction efficiency, rechargeable batteries, photodetectors,flexible video displays or monitors, and the like.

Quantum Confined Piezoelectric Effect in Strained Silicon and GermaniumNanoparticles

Amplified piezoelectric effects may be observed in quantum-confinednanocrystals 25 such as lead zirconate-titanate, gallium nitride, andindium gallium nitride. In one embodiment of the present noveltechnology, devices 100 exploit the amplified piezoelectric effects inquantum confined silicon and germanium nanocrystals 25 synthesized in astate of predetermined strain (See FIGS. 4-22).

The strain manufactured into the silicon and germanium nanocrystals 25defining the devices 100 may be further increased through intercalationof additional appropriately sized, small molecules, such as lithium,sodium, or the like. Intercalation is the typically reversible inclusionof a molecule between two other molecules. The novel devices 100incorporate the intercalation of a small intercalation atom or ion 107,such as lithium, into the crystal lattice structures of silicon and/orgermanium nanocrystals 25 to yield intercalated nanocrystals 110 withinternal stresses to further strain the crystal structure and henceincrease the energy density, and subsequently the power outputcapabilities, of the device 100.

The instant internally strained quantum confined silicon and germaniumnanocrystals 25 and/or intercalated nanocrystals 110 are deposited ontoa conductive substrate 15 into a highly ordered cohesive film 10 via theelectrophoretic deposition process as discussed above. Duringdeposition, the nanocrystals 25 self-assemble into a highly orderedstructure according to their dipole moments and define a unified Weissdomain throughout the film 10. Once electrophoretic deposition 35 of theparticles 25 is complete, a metal contact 115 is deposited via thermalevaporation or the like over the film 10 to protect the nanoparticlefilm 10 and establish a pathway for electrons to travel to be used topower an external device. The metal contact 115 is typically a highlyelectrically conductive metal, such as gold, platinum, silver, copper orthe like, and is typically between about 100 nanometers and 400nanometers thick.

EXAMPLE 3

A thin film of a mixture of size specific semiconducting nanocrystals 25was deposited via EPD on ITO coated glass, as described in the abovespecification and examples. The ultrapure prestrained semiconductingnanocrystals 25 were obtained from the Universal Nanotech Corporation,1740 Del Range Blvd., PMB 170, Cheyenne, Wyo., 82009. Typically, thenanocrystals 25 are at least about 99.99999 percent pure, more typicallyat least about 99.999999 percent pure, and still more typically, atleast about 99.9999999 percent pure. The substrate 15 and deposited film10 placed in a low oxygen environment at room temperature and thesubstrate 15 was then masked to define a desired back contact location.Next, using a thermal evaporator/vacuum coater or like device, the film10 was placed with the nanocoated side toward the material to bedeposited, at a distance of approximately 1-5 cm. A high vacuumenvironment was formed around the substrate 15 and an appropriateVoltage/Current combination is applied to vaporize the desired metal tobe deposited. The vaporized metal was deposited onto the substrate 15 tocreate a complete layer 115 that is both protective and allows forelectrical connections. In general, this deposition process may takefrom approximately 5 seconds to about 5 minutes, depending on thedesired back contact 115 thickness. Once the metal layer 115 wasdeposited, the vacuum was removed and the film 10 was allowed to returnto a typical room temperature environment. The masking was then removedin a low oxygen environment, leaving the desired metal depositionpattern on the film. A voltmeter and/or ammeter was used to confirm thatpower was being supplied by the newly created quantum energy device(QED). Using standard electrical connection techniques, multiple films10 may be connected in a series/parallel fashion to yield a device 100configured to generate the desired voltage/current supply configuration.A QED device 100 was completed and configured to power a desired load.

Quantum energy devices 100 as described above in Example 3 may beproduced from layered semiconducting nanocrystals 25, such as siliconnanocrystals. Typically, the nanocrystalline films 10 include a mixtureof multiple sizes of specific nanoparticles, ranging from 1 nm to about500 nm in diameter, although narrow, monomodal size distributors may bedesired for specific applications. Such a multimodal particle sizedistribution (PSD) yields high energy storage and/or powertransduction/generation/supply characteristics in the QED device 100.Typically, for each mode more than 95 percent of the particles fallwithin 2 nanometers of the mode dimension. In some embodiments, thenanocrystals 10 are provided in a predetermined bimodal or multimodalsize distribution, such that the nanocrystals 10 may be deposited totake advantage of more efficient packing density (see FIG. 13). Forexample, a first sublayer 90 of larger diameter particles 10 (such as 25nm) may be deposited, and a second sublayer 90 of smaller diameterparticles 25 (such as 9 nm) may be deposited thereupon, with the smallerparticles 25 preferentially sitting in the interstices defined by thefirst particles 25.

As illustrated in FIG. 14, a film of conducting nanowires 125, formedfrom such materials as such as ZnO, MgO or the like, deposited onto thesurface of the nanoparticles film 10, such as through vacuum evaporationor like techniques, may yield effects such as lower series resistanceand/or increased electrical conductivity and increased in powerdischarge capabilities of the QED. This film 125 may be in place of orin addition to the metal backing layer 115.

The typical film thickness of a single layer 10 is in the range of 200nm-1500 nm. Voltages ranging from 0.1 V-18V in a 1 cm² single layer film10 are achievable and have been verified by measurement. Currentsranging from 10 uA-50 mA are achievable in a single layer film 10 andhave been verified by measurement.

A QED device 100 has been successfully completed demonstratingindividual QED units fabricated using the EPD nanoparticles depositionmethod, described hereinabove. The individual QED units 100 are wiredtogether, in series or in parallel, to increase the total output voltageor current, respectively. The QED device 100 manufactured by the EPD ofnanoparticles 25 has demonstrated the capability to power LEDs and otherelectronic devices with similar power requirements. Combinations ofmultiple different sizes of nanoparticles 25 and types of nanoparticles25 may be used to generate QED devices 100 having specifically tailoredand desired output characteristics. Multiple layers 90 of nanoparticles25 may be utilized, and metal layers 115 may be interspersed or mixedbetween the nanoparticulate semiconducting layers 90. Metallic andnon-metallic back or front contacts 45, 115 may be utilized, dependingon the desired QED output. P-type or N-type doped semiconductor (i.e.,non-intrinsically doped) nanoparticles 25 may be utilized and/or mixedwith intrinsic semiconducting nanoparticles 25, as desired.

Quantum Energy Device (QED) Overview

In one embodiment, as shown in FIG. 14, the present novel technologyrelates to a battery 100 that utilizes the unique properties of siliconand germanium nanocrystals 25. High purity silicon or germaniumnanocrystals 25 ranging in size from about 1 nm to about 1000 nm aredeposited on to a conductive substrate 45 by use of electrophoreticdeposition (EPD). A tightly compacted thin film 10 of the silicon and/orgermanium nanocrystals 25 may range in thickness from about 100 nm toabout 2000 nm, depending on the desired properties of the film 10. Aconductive metallic back contact 115, such as aluminum, gold, silver orthe like, is applied to the thin film 10 of semiconducting nanocrystals25 in a thickness range of about 50 nm to about 500 nm. Thermalevaporation, e-beam evaporation, sputter coating, electroplating, or thelike may be used to apply the metallic back contact 115.

The silicon and germanium nanocrystals are typically synthesized with astate of stress distributed therein which slightly strains the atomicspacing of the crystal structure. This distorting or straining of thelattice imparts a piezoelectric effect which distorts the electron cloudand gives rise to a voltage potential. Direct current electrical energymay then be utilized to power electrical devices. Individual cells 100may be wired in series or parallel to supply the desired voltage andamperage needed to power a specific device.

EXAMPLE 4

A suspension 30 of pre-strained silicon nanocrystals 25 suspended intoluene 50 was obtained from the Universal Nanotech Corporation in aconcentration of approximately 100 mg per 100 ml. The suspension 30includes a mixture of nanocrystal sizes but the majority of nanocrystals25 were between approximately 10 nm and 150 nm in dimension. Thesuspension 30 was sonicated to ensure a homogeneous mixture wasobtained. Then, approximately 10 ml of homogenized suspension 30 wasadded to a glass beaker. Approximately 10 ml of acetone was then addedto the mixture. 300 microliters of 1-Butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide 65 was also added to the mixture todefine an admixture 30.

The admixture 30 was then sonicated again to ensure homogeneity andheated to a temperature of 40 degrees Celsius. A magnetic stir bar wasused during heating to facilitate an even temperature in the admixture30 and to ready the admixture for electrophoretic deposition (EPD) as anEPD bath 30. A conductive substrate 15 of glass coated with Indium TinOxide (ITO) 45 with an average resistance of 8 ohms per square cm and ofdimensions of approximately 1 cm wide by 2.5 cm long was cleaned 40 witha spray of pressurized acetone and wiped clean. The ITO glass 15 wasthen attached to the negative lead (cathode) 75 on the power supply. Ahigh purity carbon electrode 80 was attached to the positive lead(anode) on the power supply 70. The carbon electrode 80 was insertedinto the EPD bath 30.

The ITO coated glass 15 was then inserted into the EPD bath 30 to adepth of approximately 1 cm with the conductive side facing the carbonelectrode 80 and separated by a distance of approximately 1 cm. Thepower supply 70 was energized and approximately 4 volts andminimal/negligible current was applied for approximately 3 minutes.During the 3 minutes the nanocrystals 25 were deposited onto theconductive substrate 15 and were visually observed as the film 10 grewthicker and become more opaque. The power supply 70 was deenergized andthe conductive substrate 15 was removed from the EPD bath 30.

After silicon nanocrystal 25 application, lithium was deposited on tothe film through electroplating of lithium acetate dissolved in asolution of dimethylacetamide (DMA). The silicon nanocrystal film 10 wasthen submerged into the solution for electrophoretic deposition oflithium. Lithium ions 107 were intercalated into the silicon crystalstructures 110 during EPD to define a device 100 having increased chargedensity and enhanced recharging capabilities. The device 100 was thenset out to dry in a low oxygen environment at elevated temperature(about 110 degrees Celsius). It should be noted that while convenient toincrease drying rate, heat is not essential.

Within 3 hours, a metallic back contact 115 was applied to preventoxidation of the silicon thin film 10. A high purity aluminum metallicback contact 115 was applied using a thermal evaporator to a thicknessof approximately 200 nm. Masking tape, metal screens, and glass wereused to control the location of the metallic back 115 contact and toprevent the aluminum layer 115 from shorting to the ITO coated glass 15.

After the aluminum layer 115 was applied, the QED cell 100 was completeand is ready for wiring to a desired electrical device. Great care wastaken to not touch the cell area with the silicon nanocrystals film 10applied to prevent any shorting of the cell 100. A series and parallelcircuit was then created using multiple cells 100 that were produced inthe same manner. Through this process, an array of QEDs 100 were wiredto generate over 3.7 volts and 50 mA. This array 100 was then connectedto a TFT display screen and the device functioned as normal with the QEDdevice 100 supplying the electrical energy.

Typical Properties of Silicon Film of 1 square cm Volts 1.5 Amps 0.005Watts 0.0075 Battery Life (hrs) 48 Watt-Hours 0.36 Kilowatt-Hours0.00036 Megajoules (MJ) 0.001296 Grams of Si 0.00018632 Kilograms of Si1.8632E−07 MJ/Kg 6955.8 Grams/Watt-Hour 0.000518

Energy Density Comparison Alkaline 0.59 MJ/Kg Li-ion rechargeable 0.46MJ/Kg Zinc-air 1.59 MJ/Kg NiMH 0.36 MJ/Kg

The energy density observed from the arrayed QED device 100 was about7000 MJ/Kg, several orders of magnitude higher than that of an alkalinecell, a lithium-ion battery, and the like.

Another embodiment device 100 is illustrated in FIG. 15. The device 100is similar to that described above regarding FIG. 14, but with theaddition of an electrolyte 165 in contact with the intercalatednanocrystals 25 making up the film 10. The electrolyte 165 compositionis typically matched to the intercalation agent 107 composition (i.e., alithium salt electrolyte for use with lithium electrodes and/or lithiumintercalation to yield a lithium ion battery cell), such that theelectrolyte facilitates ionic conduction and allow the device 100 tofunction as a voltage source for rechargeable lithium-ion batteries.

This process may be modified in various ways to benefit mass productionand to tailor specific electrical properties. It is not possible tocover all permutations and therefore it is understood that this noveltechnology is not limited to the examples detailed above.

While the novel technology has been illustrated and described in detailin the drawings and foregoing description, the same is to be consideredas illustrative and not restrictive in character. It is understood thatthe embodiments have been shown and described in the foregoingspecification in satisfaction of the best mode and enablementrequirements. It is understood that one of ordinary skill in the artcould readily make a nigh-infinite number of insubstantial changes andmodifications to the above-described embodiments and that it would beimpractical to attempt to describe all such embodiment variations in thepresent specification. Accordingly, it is understood that all changesand modifications that come within the spirit of the novel technologyare desired to be protected.

1. A power generation device, comprising: an electrically conductingsubstrate; and a layer of internally strained semiconductingnanocrystals deposited on the electrically conducting layer; wherein theinternally strained semiconducting nanocrystals are substantiallybetween 2 nanometers and 50 nanometers across; wherein the internallystrained semiconducting nanocrystals are substantially piezoelectric;wherein the internally strained semiconducting nanocrystals are arrangedwith aligned dipole moments to define a unified Weiss domain; whereinthe layer is between about 200 nanometers and about 1500 nanometersthick.
 2. The device of claim 1 and further comprising an electricallyconducting metal layer deposited onto the layer of internally strainedsemiconducting nanocrystals.
 3. The device of claim 1 and furthercomprising a structural support layer adjacent to the electricallyconducting layer.
 4. The device of claim 1 wherein the internallystrained semiconducting nanocrystals are greater than 99.999999 percentpure.
 5. The device of claim 1 wherein the internally strainedsemiconducting nanocrystals are selected from the group includingsilicon and germanium.
 6. The device of claim 1 wherein the layer ofinternally strained semiconducting nanocrystals is 1 cm², generates avoltage of power of between about 0.1V and about 18V and a shortedcurrent of between about 10 μA and about 50 mA.
 7. The device of claim 1and further comprising an array of ZnO nanowires deposited onto thelayer of internally strained semiconducting nanocrystals.
 8. The deviceof claim 1 the respective internally strained semiconductingnanocrystals are substantially intercalated with lithium.
 9. The deviceof claim 1 wherein the energy density is at least 1000 MJ/Kg.
 10. Anelectrically transductive device, comprising: a substrate having anelectrically conducting surface portion; a first film of semiconductingnanoparticles positioned on the electrically conducting portion andfurther comprising: a first plurality of close packed first generallyspherical particles defining a first plurality of interstices; and asecond plurality of second, smaller generally spherical particlessubstantially filling the plurality of interstices; and a first coatingof electrically conductive metal deposited over the first film.
 11. Theelectrically transductive device of claim 10 and further comprising: asecond film of semiconducting nanoparticles positioned on theelectrically conductive first coating; and a second coating ofelectrically conductive metal deposited over the second coating.
 12. Theelectrically transductive device of claim 10 wherein the semiconductingnanoparticles are selected from the group including high purity silicon,high purity germanium, doped P-type silicon, doped -N-type silicon,doped P-type germanium, doped N-type germanium, and mixtures thereof 13.The electrically transductive device of claim 10 wherein the substrateif selected from the group including glass and plastic and wherein theelectrically conducting portion is indium tin oxide.
 14. Theelectrically transductive device of claim 10 wherein the substrate andelectrically conducting portion are both transparent.
 15. Theelectrically transductive device of claim 10 wherein the semiconductingnanoparticles are intercalated with lithium.
 16. The electricallytransductive device of claim 10 wherein the semiconducting nanoparticlesare piezoelectric.
 17. The electrically transductive device of claim 10wherein the energy density is at least about 1000 MJ/Kg.
 18. Anelectromechanical device, comprising: a substrate having an electricallyconductive surface; a film of piezoelectric nanoparticles positioned inelectric communication with the electrically conductive surface; anelectrically conducting metal layer positioned opposite the electricallyconducting surface and in electric communication with the film ofpiezoelectric nanoparticles.
 19. The electromechanical device of claim18, wherein the piezoelectric nanoparticles are generally spherical;wherein the piezoelectric nanoparticles have diameters between about 2and about 50 nanometers, and wherein the film is between about 500nanometers and about 800 nanometers thick.
 20. The electromechanicaldevice of claim 16 wherein film is further comprised of; a firstplurality of generally spherical piezoelectric nanoparticles withdiameters between 8 nanometers and 10 nanometers; and a second pluralityof generally spherical nanoparticles with diameters between 24nanometers and 26 nanometers.
 21. The electromechanical device of claim18 wherein film is further comprised of a multimodal distribution ofparticles; and wherein more than 95 percent of the particles definingeach respective mode are within 2 nanometers of the respective mode. 22.The electromechanical device of claim 18 wherein the piezoelectricnanoparticles are strained through intercalation.
 23. Theelectromechanical device of claim 18 wherein the energy density is atleast about 1000 MJ/kg.